Tariquidar may affect blood pressure during infusion, and there can be reduction of normal blood cells, gastrointestinal problems, and allergic reactions. The radioactive Sestamibi can cause headache, chest pain, and nausea. Radiation used in this study has been approved as involving a slightly greater than minimal risk for adults and an acceptable risk for children. This radiation is considered necessary to obtain information desired. One possible effect is a slight increase in the risk of cancer.